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Concretisation in Bengaluru amplifying heatwaves, say IISc professors

Experts call for creating more water bodies like lakes and green areas in the city to reduce the daily maximum temperatures.

India Meteorological Department's (IMD) Bengaluru city observatory recorded 151 mm of rainfall.

Although Bengaluru has recorded excess rainfall from the beginning of March, soaring temperatures have been a concern for the city. Experts put this down to global warming as well as rapid urbanisation.

Professor G Bala from the Centre for Atmospheric and Oceanic Sciences at the Indian Institute of Science (IISc) in Bengaluru said: “Every year, the southern peninsula, including Karnataka, receives pre-monsoon showers in March, April and May. What we are witnessing now is these pre-monsoon showers. There is a large year-to-year variation in the quantum of these pre-monsoon showers. Scorching heat is also usual during this period but it has become intense in recent years likely because of global warming and urbanisation.”

For the record, March 15 broke a five-year record for the maximum temperature for the month with a mark of 34.6 degrees Celsius. The maximum temperature is hovering around 32-33 degrees Celsius in April. The highest temperature recorded for April was in 2016, at 39.2 degrees Celsius.

“The expanding concretisation in the city amplifies the intensity of heatwaves… Creating more water bodies like lakes and green areas in the city will help to reduce the daily maximum temperatures,” Bala said.

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Sharing insight about his findings, Dr TV Ramachandra from the Centre of Ecological Sciences at the IISc said: “Urban growth (paved surfaces) in Bangalore has now reached 85 per cent and the vegetation cover in the city is about 3.5 per cent. Natural ecosystems – tree cover and lakes in a region as heat sinks and help in moderating microclimate. Data analyses using temporal remote sensing data (thermal band) reveals that (maximum) temperature of 19 degrees celsius in the mid-1990s , reached 26 degree celsius in 2007 and now 38 degree celsius. This is directly correlated with the loss of tree cover and lakes in the city due to senseless unplanned urbanisation. The decline of 89 per cent tree cover and 79 per cent of lakes during the past four decades highlights rapid unplanned urbanisation.”

Ramachandra suggested that the city needs to be decongested by shifting some of the major industries to other parts of Karnataka which could also help in addressing migration and ensuring job opportunities for the local people.

“The government should focus on greening the city. To begin with, we need to plan at least a mini forest in each ward. Our experiment at the IISc campus of a mini forest created in the 1990s with 49 native species and 500 saplings led to a lower temperature, enhanced groundwater table at three meters as against 10 meters in the 1990s. The absence of invasive weeds has been aiding in carbon sequestration, habitat for a wide diversity of fauna and experimental plots for education programmes for enhancing environmental knowledge. This model is now replicated in other parts of the state and some institutions in Bangalore (like K K English school, Varthur),” he elaborated.


Ramachandra also stated that rejuvenating lakes would also help in moderating microclimate, enhancing the storage capacity of lakes and improving the groundwater table.

Meanwhile, from March 1 to April 21, India Meteorological Department’s (IMD) Bengaluru city observatory recorded 151 mm of rainfall. The all-time record for April was 2001 when Bengaluru received 323.8 mm rainfall. Last year, the city recorded 118.2 mm rainfall in April and 121.11 mm in 2020.

First published on: 21-04-2022 at 02:13:34 pm
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